Rectangular bell-type furnace hood



Oct. 10, 1939. F. R. J. DAVIS RECTANGULAR BELL-TYPE FURNACE HOOD Filed Aug. 7, 1937 2 Sheets-Sheet 1 ZZ /l/l/l/ lNvENToR Heder/'CA' J D0 W5` WITNESSES:

' ATr'oRNE Oct. 10, 1939. F. R. J. DAVIS 2,175,829

RECTANGULAR BELL-TYPE FURNACE HOOD Filed Aug. 7, 1937 2 sheetsmsheet 2 27 WITNEssEs: INVENTOR Frederic/f /J @bv/'5 E 2 i 55 BY ATToR'Nl-:Y

ample, a single sheet of metal Patented Oct. l0, 1.939

lUNITED STATES PATENT OFFIC Frederick R. J. Davis,

Westinghouse Electric pany, East Pennsylvania Pittsburgh.

Irwin, Pa., assign & Manufacturing Com` Pa., a corporation. oi'

. Application August 7, 1937, Serial No. 157,853

.10 Claims.

My invention relates to annealing furnaces and the like and'particularly to rectangular bell-type furnace hoods therefor.

In some rectangular hoods for such furnaces known to the art, partially fluted sides 'and top portions have beenV employed. However, this structure could not be used with a skirt as it -will not permit the proper expansion and contraction between the hoods proper and the skirt. Moreover, the iiuted portions of the sides and tops have extended to within a few inches from the junction between the top plate and the sides. The inability to extend the flutes in a continuous path up one side, acoss the top and'down the other side lhas furtherl limited the field of application of the rectangular hoods because, by not having the iiutes in such a cont' uous path, the hoods cannot freely expand and contract.

Different manners of forming the sides and top of the hood are well known to the art. For exmay be made to extend vertically as one side of the hood, be bent or otherwise formed to extend horizontally to form the top of the hood, and then bent or otherbeing welded to the edge thereto. Whatever constructwn is employed, it is usual to provide transverse corrugations or flutes in the sheets to permit expansion and contraction of the hood, as well as to stengthen it.

In a construction where a weld is present between a side wall and the top wall I have tried placing right angle flute inserts directly between the-top and side flutes in which the weld between such flutes and inserts joined at the junction of the top plate and side walls. While this structure will satisfactorily operate for. a certain length oi' time, since it necessarily involves the ing, sooner or later the expansion and contraction of the hood will weaken the weld at this u overstressing of the weld joints.

A further object of my invention is to provide a iluted hood having. a skirt which will be capable of expansion and contraction with respect to the outer edge of the skirt` without causing undue distortion of the hood.

Another object ot niv invention is to provide a ed hood which will not have any welded junction located within the flutes or in the flutes at the bend between the top and the side and which will be sumciently strong and safe enough to guardfagainst the loss of gas located therein.

Other objects of my invention will either be pointed out specincallyin the course of the following description of a device embodying my invention, or will be apparent from such description.

In the accompanying sheets of drawings:

Figure 1 is a transverse sectional view of a device such as an annealing furnace embodying my invention; 20

Fig. 2 is a view similar to Fig. 1 showing a modified form of my invention;

Figs. 3 and 4 are a top view and a side elev'ational view, respectively, of the hood shown in Fig. 1; 25

Fig. 5 is a sectional view taken along line V-V of Fig. 3:

Figs. 6 and 7 are sectional views taken along lines corresponding to line VII-VII of Fig. 3 showing partial sectional views of modified corners of the hoods shown in Figs. l and 2;

Fig. 8 is a sectional view taken along` line VIII-VIII of Fig. 3; ,f Figs. 9 and 10 are detail views of the nuted insert bend shown in Fig. 5, and

Fig. 11 is a perspective view of a nute, showing in particular a bend thereof of the type illustrated in Fig. 5..

Referring to Figures 1, 3 and 4, I show a rectangular bell-type furnace I0 including a furnace I2 and a base I4, a rectangular iluted hood I6 (or Il Fig. 2) being located within the bell I2.

The rectangular furnace bell I2 may be composed of re clay brick 2l or'of any other suitable material which will not break down under the heat, substantially 1500 to 1700 F., to which it will be subjected. The heat may be .supplied to the furnace by means of suitable electric heating elements 22, for example, located on the inbell inany suitable manner. understood that heat may be supplied to the furnace ln any other desired manner. A suitable supporting plate 24 may be located in the bottom portion of the furnace bell I2 to rigidly support the i'ire clay brick 2U. A 55 prises upstanding 2 suitable bar 26 may be rigidly attached below and near each side of the plate 24 to support the furnace bell I2 upon the outer part of a skirt 21 preferably integral with iluted hood i6, as hereinafter described, and at a suitable distance above the base I4, so that the weight of such furnace bell will not be carried upon the inner or fluted part of skirt 21, and to permit such weighted skirt to function as a preliminary gas seal. The furnace bell I2 may be removed from or replaced on the'base I4 by means of a hook (not shown), or by any other suitable means.

The furnace base I4 may be constructed-in any suitable manner. However, it is preferred that such base be composed of nre` clay brick having such compression strength that it will adequately support the furnace bell l2, the hood I6 and any desired charge located within the hood. An upwardly protruding hearth 2l may be located substantially in the center of the furnace base I4 and may have a hearth plate Il located thereonfor supporting any desired charge. A trough 32 may be located along the outer edge of the base I4 for holding any suitable sealing medium I4, such as oil. which may be operatively associated with the hood It by means of the skirt 21, es hereinafter described.

'I'he rectangular iluted bell-type hood I8 comside walls 40 and a top plate 42. The side walls 4l -have located, preferably integrally, therein, a plurality of flutes 44 extending from substantially the bottom edge to the top edge thereof. Likewise, the top plate 42 has a plurality of preferably integral flutes 48 extending transversely across such plate to register and cooperate with the vertically upstanding iiutes 44. In addition, the hood I8 of Fig. 1 includes the skirt 21 extending substantially at right angles to the side walls 40, and which has located theron flutes 50 which register and cooperate with the flutes 44 located within the side walls 40.

The top plate 42 may be formed as a separate integral piece free from the side walls 40 and may be rigidly attached thereto by welding its edges to the top edges of the side walls, although a portion of the top plate 42 may be integral with one side wall.

However, it is preferred that the hood side walls 40 and top plate 42 be shaped from a continuous sheet oi' material extending upwardly from substantially the bottom edge of one of the side walls to form such side wall, across the top to form the top plate, and downwardly to form the opposite side wall. The ilutes 44 and 44 may also be formed in the continuous sheet to necessary expansion joints and stifiening. Such flutes will then be in a continuous path, without having any welds therein, progressing up one side wall across the top and down the opposlte'side wall. The shape of the flutes as the chanac from a vertical flute 44 to the horizontal flute 44 occurs will then be substantially as shown in Fig. '1. By using the preferred constructions of Figa 1A and 2, which, as h ve described, has the side walls 4I and top plate .42 formed from a oontinuous sheet of material with the'flutes 44 and 44 formed therein, there willebe no welds in the nutes located st the junction between the top plate and the side walls. This will permit the top portion of the nood to expand and contract transversely ss well as longitudinally without any danger of warpins the hood orv of a fracture between the side walls 4l and top plate 42 them' selves or between the nutes 44 and 44, thereby individual sheets or from a smesso ensuring a permanent, flexible, impervious enclosure for the gas located within it.

When the construction of the hood is such that one or both side walls are formed independently of the top wall, a weld joint is usually employed to unite the parts into a unitary structure. With such construction the flute 46 inl the top wall is made functionally continuous, in my construction, with the side flute 44 by means of an irregularly-shaped iiute insert 52,

preferably of the form shown in Figs. 9 and l0, welded in position gated to form a diagonal ute with two upstanding ends 58' preferably having acute angles somewhat less than a right angle. The side 4c and top 42 (Fig. 1l) are properly cut out to mate with the insert. When welded in position, the junction of `the corner of the ends Il and the bend between the side and top wall is spaced from the ute portion of the insert so that this junction is not subjected to bending stresses or to forces at right angles which would be the case if a customary right angular corner insert were employed. The stresses at the junctions 5l' are now between the insert and top or between the insert and side wall, and at no point ofthe flute of the insert do the stresses, created by changes in the top, side wall, and flute, act simuutaneousiy. ,f

It may be observed, then, that the insert 52 is welded to the vertically upstanding flutes 44 and to the horizontal flutes 46, at some distance from the junction of side wall 40 and wp plate 42, thereby forming a continuous flute progressing up on one side wall, across the top plate and down the other side wall.

By having the irregularly shaped ilute insert 52 located between the top ilutes 48 and the side flutes or junctions on the flutes in line with the integral or welded junction of the top andside walls.

It is to be understood that the flute insert I2, shown in Figs. 5, 9, l0 and 1l may be used to obtain the bend between the top flutes 44 and side flutes 44, regardless of whether the top-plate 42 and side walls 40 are formed from single sheet. However, when the insert 52 is used with the single sheeted hood it is obvious that it 1s not necessary to form ilute cornerbends in such sheet, it merely being necessary to form the top and side flutes will be no welds located within the the top and side that there flute in line walls.

As an additional modification, the top plate 42 may be somewhat smaller than the distance between the side walls 4l and disposed somewhat above the edge of the side walls, the plane between the edges of the walls preferably forming a 45 angle as shown more particularly in Fig. 6, and an additional nuted plate 54, with the iiutes il thereof trspemidal in side elevation, may be `depending portion 5l to make it gas-tight.

'I'he skirt 21 located at the bottom portion of the hood i6 is rigidly attached to the side and end walls 40 of such hood, preferably by welding. A depending portion Il is located at the outside ends of the skirt 21 to project downwardly into the sealing trough I2 and into the sealing medium Il, preferably oil, to produce a gas-tight seal ior the hood.' The skirt 21 is of such a length, with respect to the furnace bell l2 and iluted hood i6, that it extends outside the furnace bell I2. Because the outside end and of the skirt 21 extend outside the furnace, the temperatures of such portions o'f the skirt 21 will be considerably below the temperature within the furnace bell. inside temperature may be 1500 to l700 F., while the outside temperature is substantially 150 F.

Due to the extreme diilerenc in temperature between the inside and the outside of the iluted hood I8 it is necessary to provide additional means for permitting the inside portion of the skirt 21 to expand and contract with respect to the outside portions thereof. To permit this expansion and contraction, without undue warpage of the hood il, including skirt 21, it is necessary to slot the inside portion of the skirt 21 substantially normal to the plane of the side walls. These slots 80, shown in Figs. 6, 7 and 8 are covered by the utes il which also extend substantially at right angles to the side walls of the hood I6. The flutes 5U are rigidly attached to the skirt, preferably by welding. The slots 80 in cooperation with the flutes permit the inside portion of the skirt 21 to expand and contract transversely to the slots 80, with respectto the outside portion cf the skirt 21, without causing the skirt to warp. The cooperation of flute Il with skirt 21, inasmuch as they are rigidly attached thereto and form a gas-tight seal therewith, prevents the controlled atmomhere located within the hood from leaking out via the slots Il.

The flutes Il and end wall flutes Bla located over the slots. cooperate with and are rigidly attached to the nutes Il and Ma, respectively, in such a manner that their Junction will be gastight. By having the flutes Il cooperate with' the flutes M, it is obvious that flutes will be provided which extend'continuously along the skirt, up one side, across the top, down the other side and along the Wposite side of the skirt.

By having the ilutes Il extendingfout over slots the skirt 21, and by having .l located within continuous cooperative flutes progressing transversely of the walls of hood 4l. such hood II. in-

cluding the inner portion of skirt 21, may expand and contract freely .without serious distortion with respect to the outer edge of the skirt.

If it bepreferred, a plurality of troughs Il may `belocatedashortdistancefmmthehearth2las showninr'lg-2inwhichasuitablesandsealll maybelocatedandsuchsandsealllmaybe med with bell-typebood It whiohdcesnot have between the top flutes and nace, except hood lldoes not have a skirt asso- 5 ciated therewith.

I'he top plate and the top portion of the side walls of the hoods il and Il, when expanding, bow upwardly and outwardly with respect to the Junction of the top and side walls, as hereinabove described, or employing a ilute insert such as 52, 2s or a corner plate Il properly nuted, the tendency for cracks to develop at the bends is substantially eliminated. This reduction in the possibility of cracks developing is especially true where the nutes u and u, side wins n and top plate I2 areshaped from one continuous sheet, as shown in Fig. 7, as there are no longitudinal welds necessary at the bends of the flutes, and, therefore. the internal stresses and strains cannot be concentrated at one point at such bend.

`It is to be understood that there may be longitudinal welds within the hoods il and I8 at points other than the bends within the flutes, sucl-I as along lines B2 or Il as shown in Fig. 7, without increasing the stresses at the ilute bends or causing such bends to fracture.

It is, therefore, obvious that by using the preferred form of structure as hereinabove described, in which the sidewalls, top plate and the flutes located therein are formed from one continuous sheet without having any welds located within the flutes, such structure will not rupture at the bend the side flutes.

It is to be understood, however, that if the over-al1 length oi the nuted hood is greater than the width of commercial sheets and it be desired to have the utes run parallel to the longitudinal aids of the sheets, such hood may be formed of two or more sheets welded together parallel with the hood's transverse axis. as shown by line-Il 55 in Figs. 3 and 4, so that the ilutes will be entirely within one sheet and extend Parallel to the transverse axis of such hood. The hood may also be shown by line l2 in l'lg. 8. It therefore follows thatif the hood be formed ofa plurality o! sheets, the Junctions -therebetween may extend parallel withatransverse linethroughthehoodsndmay belocated at points remote from the ilute bends, as shownbylines Il and Il respectively. in Figs. 3 and 4. j

It is,theretore. obviomthathoodssshereinabove describedmsybsussdwithinabelltyps mrnaceandoparstedthloughrepeated cycles without any danger of the hood fracturing at the junction or bend between the top flutes and the side flutes, and that due to such fluted structure oi' the hood, such hood may expand and contract in relation to the outer edge of the skirt located integrally therewith.

I desire it to be understod that the term continuous flute in the appended claims, is employed to cover any on the drawings which, whether integrally or otherwise formed, provide uninterrupted or gastight flutes or channels.

Various further n odifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall bel placed thereon as are imposed by the prior art and the appended claims.

I claim as my invention:

i. In a rectangular bell type furnace,.a rectangular hood including substantially vertical side walls, a top plate and a skirt, a plurality of continuous flues running along at least a portion of said skirt, up one side, across the top, down the other side of the hood, and means comprising said flutes for permitting the expansion and contraction of said hood.

2. In a rectangular bell type furnace, a rectangular hood including substantially vertical side walls, a top plate and a skirt, a continuous sheet of material extending upwardly to form one of said side walls, across the top to form the top plate and downwardly to form the other of said side walls,-a plurality of continuous flutes running along atleast a portion of said skirt, up one side, across the top, and down the other side of said hood, and means comprising said flutes for permitting the expansion and contraction of said hood.

3. In a rectangular bell-type furnace, a rectangular hood including substantially vertical side walls, a top plate, and a skirt, said side Walls, skirt and top plate comprising a plurality of sheets rigidly attached together, a plurality of continuous flutes, each entirely formed in one sheet, their ends registering so that the flutes as a whole run along at least a portion oi' said skirt, up one side, across the top and down the other side, and means comprising said flutes for permitting the expansion and contraction of said hood with respect to the skirt.

4. In a rectangular bell type furnace, a rectangular hood including substantially vertical side walls and a top plate and a slotted skirt, a continuous sheet of material extending upwardly to form one of said side walls, across the top to form the top plate and downwardly to form the other of said side walls, a plurality of continuous flutes running along at least a portion of said skirt and over said top and down the other side of said hood, and means comprising said slotted skirt and flutes for permitting the expansion and contraction of said hood with respect to the skirt.

of the types of flutes shown slots, up one side, across the 5. In a rectangular bell-type furnace, a rectangular hood comprising joined top and side walls, .alined flutes therein terminating short of the junction of the corresponding walls, a foursided insert with a diagonally-extending, central flute therein having two opposite non-fiuted corners'disposed in alinmenet with said junction and being secured to the adjacent walls along parts of its edges extending away from said corners, the flute in said insert being secured at its respective ends to the adjacent flutes in said walls.

6. In a rectangular bell-type furnace, a rectangular hood comprising joined top and side walls, alined flutes therein terminating short of .the junction of the corresponding walls, the

terminating planes of said flutes converging inwardly, and an insert having a flute therein, the ends of said insert flute being secured to said converging ends of said wall flutes to form acontinuous gas-tight (passage.

7. In a furnace, a rectangular hood comprising continuous substantially vertical side Walls and an intermediate top wail, said walls including at least one continuous, transverse flute, said ilute comprised of a substantially centrally fluted insert disposed at the junction of said top wall and one of said sidewalls, said insert being so shaped `and welded to said walls that the weld points at the common junctions of the insert, said top wall, and said one side wall are removed from said flute. f

8. In a furnace, a rectangular hood comprising joined top and side walls,transverse aligned flutes in said walls, and a fiuted insert forming a connecting bend for said flutes whereby to render the same functionally-continuous, said insert being shaped to be secured to said hood at the junction of said top and side walls along lines extending from the flute and angularly related to the junction of said walls, said insert being secured to said walls in a substantially gas-tight manner. A

9. In a furnace of the type having therein a substantially gas-tight hood for enveloping a charge resting on a base, a hood comprising a side wall having upstanding flutes therein, a horizontal skirt secured to the bottom of said wall, said skirt having slots extending from the secured edge for some distance toward the other edge, and flute structures secured to said skirt and said flutes and above said slots in a gastight manner. l

l0. In a furnace of the type having therein a substantially gas-tight hood for enclosing a charge space, said hood comprising a side wall and top wall having transverse flutes, said walls having edges terminating short of each other and at an angle to both of substantially 45 degrees, and a fluted plate secured in a gas-tight manner to said edges whereby to seal the walls, the flutes of said plates being aligned with the flutes in said walls.

FREDERICK R. J. DAVIS.

CERTIFICATE OF CORRECTION.

October 10, 1959,

atent No.v 2,175,829. .i

FREDERICK R. 'J. DAVIS. I

It is hereby certified that error appears in the printed specification l'of the above numbered patent requiring correction as follows': Page 5, first column, line 9, for "platt" read -p1s.te page lilfirst column, line 25, claim l, for 'flues" read `f1utes; and that the said Letters Patent should be read with this correction therein that the same may conform to` the record of the case in the Patent Office.

Signed and sealed this 27th day of July;A A. D. 1%3..l

` Henry Van Arsdale, (Seal) Acting Commissioner of Patents.' 

